Guard columns for gas chromatographs and gas chromatograph-mass spectrometers

Abstract

The present invention discloses a gas chromatograph assembly. In one implementation, the assembly includes a sample injector and a guard column assembly. The guard column assembly includes a guard column connected to and downstream of the sample injector; a jacket with low thermal mass surrounding the guard column; a temperature controlled heater connected to the jacket to control the temperature of the jacket and thereby the temperature of the guard column; and an insulating housing surrounding the jacket. An analytical column is connected to and downstream of the guard column.

1. A gas chromatograph assembly comprising:
 a sample injector; 
 a guard column assembly including:
 a guard column connected to and downstream of the sample injector; 
 a jacket with low thermal mass surrounding the guard column; 
 a temperature controlled heater connected to the jacket to control the temperature of the jacket and thereby the temperature of the guard column; and 
 an insulating housing surrounding the jacket; and 
 
 an analytical column connected to and downstream of the guard column. 
 
     
     
       2. The gas chromatograph assembly of  claim 1 , wherein the guard column is replaceable. 
     
     
       3. The gas chromatograph assembly of  claim 1 , further comprising:
 a first fitting connecting the sample injector to the guard column; and 
 a second fitting connecting the guard column to the analytical column; and 
 wherein the jacket abuts the first and second fittings such that the temperature controlled heater also controls the temperature of the first and second fittings. 
 
     
     
       4. The gas chromatograph assembly of  claim 3 , wherein the jacket completely surrounds the first fitting and partially surrounds the second fitting and further comprising:
 a bracket abutting the second fitting; and 
 a fitting jacket connected to the bracket and surrounding the portion of the second fitting not surrounded by the jacket. 
 
     
     
       5. The gas chromatograph assembly of  claim 3 , wherein the first and second fittings comprise a zero dead volume fitting. 
     
     
       6. The gas chromatograph assembly of  claim 1 , wherein the jacket is constructed of aluminum alloy. 
     
     
       7. The gas chromatograph assembly of  claim 1 , wherein the jacket is constructed of at least two separable pieces that allow access to the guard column when separated. 
     
     
       8. The gas chromatograph assembly of  claim 1 , wherein the temperature controlled heater is a nickel-chromium heater. 
     
     
       9. The gas chromatograph assembly of  claim 1 , further comprising a temperature detector in the jacket. 
     
     
       10. The gas chromatograph assembly of  claim 9 , wherein the temperature detector is a resistance temperature detector. 
     
     
       11. The gas chromatograph assembly of  claim 1 , wherein the insulating housing is constructed of a non-asbestos high temperature calcium silicate refractory material. 
     
     
       12. The gas chromatograph assembly of  claim 1 , wherein the insulating housing is constructed of at least two separable pieces that allow access to the jacket when separated. 
     
     
       13. The gas chromatograph assembly of  claim 1 , wherein the temperature of the guard column is controlled independently of the analytical column. 
     
     
       14. A gas chromatograph assembly comprising:
 a sample injector; 
 a guard column assembly including:
 a replaceable guard column connected to and downstream of the sample injector; 
 a first fitting connecting the sample injector to the guard column; 
 a second fitting connecting the guard column to the analytical column; 
 a jacket with low thermal mass surrounding the guard column, 
 a temperature controlled heater connected to the jacket to control the temperature of the jacket and thereby the temperature of the guard column, wherein the jacket abuts the first and second fittings such that the temperature controlled heater also controls the temperature of the first and second fittings; and 
 an insulating housing surrounding the jacket; and 
 
 an analytical column connected to and downstream of the guard column. 
 
     
     
       15. The gas chromatograph assembly of  claim 14 , wherein the first and second fittings comprise a zero dead volume fitting. 
     
     
       16. The gas chromatograph assembly of  claim 14 , wherein the jacket is constructed of aluminum alloy. 
     
     
       17. The gas chromatograph assembly of  claim 14 , wherein the jacket is constructed of at least two separable pieces that allow access to the guard column when separated. 
     
     
       18. The gas chromatograph assembly of  claim 14 , wherein the temperature controlled heater is a nickel-chromium heater. 
     
     
       19. The gas chromatograph assembly of  claim 14 , further comprising a temperature detector in the jacket. 
     
     
       20. The gas chromatograph assembly of  claim 19 , wherein the temperature detector is a resistance temperature detector. 
     
     
       21. The gas chromatograph assembly of  claim 14 , wherein the insulating housing is constructed of a non-asbestos high temperature calcium silicate refractory material. 
     
     
       22. The gas chromatograph assembly of  claim 14 , wherein the insulating housing is constructed of at least two separable pieces that allow access to the jacket when separated. 
     
     
       23. The gas chromatograph assembly of  claim 14 , wherein the temperature of the guard column is controlled independently of the analytical column. 
     
     
       24. The gas chromatograph assembly of  claim 14 , wherein the jacket completely surrounds the first fitting and partially surrounds the second fitting and further comprising:
 a bracket abutting the second fitting; and 
 a fitting jacket connected to the bracket and surrounding the portion of the second fitting not surrounded by the jacket. 
 
     
     
       25. A gas chromatograph assembly comprising:
 a sample injector; 
 a first guard column assembly including:
 a first guard column connected to and downstream of the sample injector; 
 a first jacket with low thermal mass surrounding the first guard column; 
 a first temperature controlled heater connected to the first jacket to control the temperature of the first jacket and thereby the temperature of the first guard column; and 
 a first insulating housing surrounding the first jacket; 
 
 an analytical column connected to and downstream of the guard column; 
 a second guard column assembly including:
 a second guard column connected to and downstream of the analytical column; 
 a second jacket with low thermal mass surrounding the second guard column; 
 a second temperature controlled heater connected to the second jacket to control the temperature of the second jacket and thereby the temperature of the second guard column; and 
 a second insulating housing surrounding the second jacket; and 
 
 an outlet connected to and downstream of the second guard column. 
 
     
     
       26. The gas chromatograph assembly of  claim 25 , wherein the first and second guard columns are replaceable. 
     
     
       27. The gas chromatograph assembly of  claim 25 , further comprising:
 a first fitting connecting the sample injector to the first guard column; 
 a second fitting connecting the first guard column to the analytical column, wherein the first jacket abuts the first and second fittings such that the first temperature controlled heater also controls the temperature of the first and second fittings; 
 a third fitting connecting the analytical column to the second guard column; and 
 a fourth fitting connecting the second guard column to the outlet, wherein the second jacket abuts the third and fourth fittings such that the second temperature controlled heater also controls the temperature of the first and second fittings. 
 
     
     
       28. The gas chromatograph assembly of  claim 27 , wherein the first jacket completely surrounds the first fitting and partially surrounds the second fitting and wherein the second jacket completely surrounds the fourth fitting and partially surrounds the third fitting and further comprising:
 a first bracket abutting the second fitting; 
 a first fitting, jacket connected to the bracket and surrounding the portion of the second fitting not surrounded by the first jacket; 
 a second bracket abutting the third fitting; 
 a second fitting jacket connected to the bracket and surrounding the portion of the third fitting not surrounded by the second jacket. 
 
     
     
       29. The gas chromatograph assembly of  claim 25 , wherein the first, second, third, and fourth fittings comprise a zero dead volume fitting. 
     
     
       30. The gas chromatograph assembly of  claim 25 , wherein the first and second jackets are constructed of aluminum alloy. 
     
     
       31. The gas chromatograph assembly of  claim 25 , wherein the first and second jackets are constructed of at least two separable pieces that allow access to the first and second guard columns when separated. 
     
     
       32. The gas chromatograph assembly of  claim 25 , wherein the first and second temperature controlled heaters are nickel-chromium heater. 
     
     
       33. The gas chromatograph assembly of  claim 25 , further comprising a first temperature detector in the first jacket and a second temperature detector in the second jacket. 
     
     
       34. The gas chromatograph assembly of  claim 33 , wherein the first and second temperature detectors are resistance temperature detectors. 
     
     
       35. The gas chromatograph assembly of  claim 25 , wherein the first and second insulating housings are constructed of a non-asbestos high temperature calcium silicate refractory material. 
     
     
       36. The gas chromatograph assembly of  claim 25 , wherein the first and second insulating housings are constructed of at least two separable pieces that allow access to the first and second jackets when separated. 
     
     
       37. The gas chromatograph assembly of  claim 25 , wherein the temperature of the first and second guard columns is controlled independently of the analytical column. 
     
     
       38. A replaceable guard column assembly for a gas chromatograph assembly having a sample injector for introducing a sample into the gas chromatograph assembly and an analytical column for analyzing the sample, the guard column assembly comprising:
 a replaceable guard column connected to and downstream of the sample injector and connected to and upstream of the analytical column; 
 a jacket with low thermal mass surrounding the guard column; 
 a temperature controlled heater connected to the jacket to control the temperature of the jacket and thereby the temperature of the guard column; and 
 an insulating housing surrounding the jacket. 
 
     
     
       39. The replaceable guard column assembly of  claim 38 , further comprising:
 a first fitting connecting the sample injector to the guard column; and 
 a second fitting connecting the guard column to the analytical column; and 
 wherein the jacket abuts the first and second fittings such that the temperature controlled heater also controls the temperature of the first and second fittings. 
 
     
     
       40. The replaceable guard column assembly of  claim 39 , wherein the jacket completely surrounds the first fitting and partially surrounds the second fitting and further comprising:
 a bracket abutting the second fitting; and 
 a fitting jacket connected to the bracket and surrounding the portion of the second fitting not surrounded by the jacket. 
 
     
     
       41. The replaceable guard column assembly of  claim 38 , wherein the first and second fittings comprise a zero dead volume fitting. 
     
     
       42. The replaceable guard column assembly of  claim 38 , wherein the jacket is constructed of aluminum alloy. 
     
     
       43. The replaceable guard column assembly of  claim 38 , wherein the jacket is constructed of at least two separable pieces that allow access to the guard column when separated. 
     
     
       44. The replaceable guard column assembly of  claim 38 , wherein the temperature controlled heater is a nickel-chromium heater. 
     
     
       45. The replaceable guard column assembly of  claim 38 , further comprising a temperature detector in the jacket. 
     
     
       46. The replaceable guard column assembly of  claim 45 , wherein the temperature detector is a resistance temperature detector. 
     
     
       47. The replaceable guard column assembly of  claim 38 , wherein the insulating housing is constructed of a non-asbestos high temperature calcium silicate refractory material. 
     
     
       48. The replaceable guard column assembly of  claim 38 , wherein the insulating housing is constructed of at least two separable pieces that allow access to the jacket when separated. 
     
     
       49. A gas chromatograph assembly comprising:
 means for injecting a sample; 
 means for removing impurities from the injected sample; 
 means for controlling the temperature of the impurity removing means including means for creating an air bath surrounding the means for removing impurities; 
 insulating means surrounding the means for creating an air bath, wherein the insulating means is separate from the means for creating an air bath; and 
 means for separating chemical components of the injected sample, 
 wherein the impurities removing means is located upstream of the separating means. 
 
     
     
       50. The gas chromatograph assembly of  claim 49 , wherein the impurities removing means is replaceable. 
     
     
       51. The gas chromatograph assembly of  claim 49 , wherein the means for controlling the temperature of the impurity removing means includes means for heating the air bath.